Matching the variable's data type to the file data

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Which declaration suits a variable that will hold a line of text read from a file?

A DECLARE LineOfText : INTEGER

B DECLARE LineOfText : STRING

2. A file stores the whole number 42. Which declaration suits the variable used with READFILE?

A DECLARE Score : INTEGER

B DECLARE Score : BOOLEAN

3. Which statement about the variable used with READFILE is correct?

A Its data type should suit the data in the file

B Its data type does not matter, any type works

4. A student wants to write the line "Hello class" to a file. Which variable type should they declare?

A STRING

B INTEGER

5. What is the problem with this code? DECLARE Age : STRING then WRITEFILE "Ages.txt", Age, when Age should be a whole number.

A WRITEFILE can never be used with a variable

B The type should be INTEGER to suit a whole number

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1DECLARE LineOfText : STRING		ALine is meant to hold a line of text but is declared as INTEGER, so the text cannot be stored. It should be declared as STRING.
2DECLARE Score : INTEGER		BDECLARE Total : INTEGER WRITEFILE "total.txt", Total
3Choose the type when you declare the variable: a line of text needs a STRING variable before it is used with READFILE		CCreates a variable that can hold a whole number stored in a file
4A whole number written to a file should be held in an INTEGER variable		DAge holds a whole number but is declared as STRING, so using it in arithmetic causes an error. It should be declared as INTEGER.
5DECLARE Age : STRING READFILE "ages.txt", Age Total ← Age + 1		EDECLARE Name : STRING READFILE "names.txt", Name
6DECLARE Line : INTEGER READFILE "poem.txt", Line		FCreates a variable that can hold a line of text read from a file or written to a file

Definitions

DECLARE LineOfText : STRING

Fill in the Blanks

Complete each line of code by filling in the missing parts.

DECLARE LineOfText : ______ READFILE "story.txt", LineOfText

DECLARE Score : _______ READFILE "scores.txt", Score

DECLARE Mark : INTEGER READFILE "marks.txt", ____

DECLARE Total : _______ Total ← 250 WRITEFILE "total.txt", Total

DECLARE Line : STRING OPENFILE "poem.txt" FOR READ ________ "poem.txt", Line

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A DECLARE Total : INTEGER

B OPENFILE "total.txt" FOR READ

C READFILE "total.txt", Total

D Total ← Total + "10"

E CLOSEFILE "total.txt"

Question 2

A DECLARE Score : INTEGER

B OPENFILE "score.txt" FOR WRITE

C Score ← "eighty-five"

D WRITEFILE "score.txt", Score

E CLOSEFILE "score.txt"

Question 3

A DECLARE Name : STRING

B DECLARE Age : STRING

C OPENFILE "pupil.txt" FOR READ

D READFILE "pupil.txt", Name

E READFILE "pupil.txt", Age

F OUTPUT Age + 1

Question 4

A DECLARE Total : INTEGER

B DECLARE Sentence : TEXT

C OPENFILE "story.txt" FOR READ

D READFILE "story.txt", Sentence

E Total ← LENGTH(Sentence)

F OUTPUT Total

Question 5

A DECLARE Message : STRING

B OPENFILE "msg.txt" FOR WRITE

C Message ← 100

D WRITEFILE "msg.txt", Message

E CLOSEFILE "msg.txt"

Answer Key

Matching the variable's data type to the file data

Section A: Quick Questions

B — DECLARE LineOfText : STRING

A — DECLARE Score : INTEGER

A — Its data type should suit the data in the file

A — STRING

B — The type should be INTEGER to suit a whole number

Section B: Match the Pairs

DECLARE LineOfText : STRING → Creates a variable that can hold a line of text read from a file or written to a file

DECLARE Score : INTEGER → Creates a variable that can hold a whole number stored in a file

Choose the type when you declare the variable: a line of text needs a STRING variable before it is used with READFILE → DECLARE Name : STRING READFILE "names.txt", Name

A whole number written to a file should be held in an INTEGER variable → DECLARE Total : INTEGER WRITEFILE "total.txt", Total

DECLARE Age : STRING READFILE "ages.txt", Age Total ← Age + 1 → Age holds a whole number but is declared as STRING, so using it in arithmetic causes an error. It should be declared as INTEGER.

DECLARE Line : INTEGER READFILE "poem.txt", Line → Line is meant to hold a line of text but is declared as INTEGER, so the text cannot be stored. It should be declared as STRING.

Section C: Definitions

DECLARE LineOfText : STRING — The variable used with READFILE or WRITEFILE needs a data type that suits the data: STRING for a line of text, INTEGER for a whole number. A wrong type causes errors.

Section D: Fill in the Blanks

DECLARE LineOfText : STRING
READFILE "story.txt", LineOfText

DECLARE Score : INTEGER
READFILE "scores.txt", Score

DECLARE Mark : INTEGER
READFILE "marks.txt", Mark

DECLARE Total : INTEGER
Total ← 250
WRITEFILE "total.txt", Total

DECLARE Line : STRING
OPENFILE "poem.txt" FOR READ
READFILE "poem.txt", Line

Section E: Spot the Error

D — Total is an INTEGER read from the file, so you can only add a whole number to it. "10" is a string. It should be Total ← Total + 10.

C — Score is declared as INTEGER, so it must hold a whole number. A string cannot be stored in it. It should be Score ← 85.

B — Age holds a whole number and is used in the sum Age + 1, so it must be declared as INTEGER, not STRING. It should be DECLARE Age : INTEGER.

B — TEXT is not a data type in 0478 pseudocode. A line of text read from a file needs the STRING type. It should be DECLARE Sentence : STRING.

C — Message is a STRING variable for a line of text, so it cannot be given a whole number. It should be Message ← "Hello".